Ethernet over Mains

Since the whole house is not wired with Cat 5 cable I have had to use Mains over ethernet to provide some networking. However after our building works the mains in our house is now split in two with two fuse boxes (containing circuit breakers and RCDs) which then have separate tails leading to the electricity board fuse.


1Needless to say the computer that drives the Sun Rays is on one mains fuse box and the Sun Ray in the kitchen is on the other.

You can see the effect of the extra hop in the screen shot. Rather than the maximum 85Mbps when the two mains bricks are on the same fuse box that reduces to a paltry 13 Mbps thanks to the hop to the Electricity board fuse and back. This explains why that Sun Ray photo frame sometimes looses connection with the server when updating the picture. The other Sun Ray in Sues Office works like a dream2.

Clearly using these to form a network between buildings would not fly. That does however not stop me from being paranoid enough to have blotted out the ethernet addresses and passwords from the screen shot.

I can see that if in the final network set up I have to have devices on both fuse boxes I will have to run them as separate networks which will cost me one extra mains over ethernet brick.


1Yes this is a windows only application. However I did grab this screen shot using a VNC session on Solaris.

2Except when the server will occasionly on booting negotiate the ethernet switch down to 100Mbs rarther than 1Gb at which point things are much more sluggish, so I have a cron job that checks the speed and warns me of this.

Comments:

Do you think the link is actually dropping? The speed shouldn't have anything to do with the Sun Ray losing a connection. You'd probably due well to force the BW limit on this DTU since compression doesn't really kick in until the 7 Mbps range. You can do this with the GUI firmware. Ping me if you need more details.

Posted by ThinGuy on December 19, 2007 at 09:56 AM GMT #

It is interesting that you find SunRay performance is better with a 1Gbs link, on my home setup I discovered SunRay performance actually improved with the server and SunRay both on 10/100 speed links. I suspect my problem was down to the switch not caching UDP very well, resulting in 30% packet loss as reported by utquery. To improve performance I ended up putting a second 10/100 nic in for sunray to work around the problem. I guess this just shows how bad the switch I have is.

Posted by James Legg on December 20, 2007 at 01:16 AM GMT #

@ThinGuy

Yes I think it is dropping. Occasionally when the photo update is happening I get the OSD icon and the n the Sun Ray will either recover or reset and then recover. So while the low bandwidth settings may help the real solution is to fix the network. However fixing the network will take time so if I can turn on the low bandwidth settings remotely (the Sun Ray is well hidden and has no keyboard or mouse) I'd like to give that a go.

@James Legg

I think it was more that at 100Mbs the server's interface would get overwhelmed and I was seeing 50% packet loss occasionally and 30-40% regularly to the Sun Ray. I now only see that sort of packet loss to the appliance that is on the wrong fuse box on the ethernet over mains network.

Posted by Chris Gerhard on December 20, 2007 at 03:06 AM GMT #

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This is the old blog of Chris Gerhard. It has mostly moved to http://chrisgerhard.wordpress.com

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